Among the numerous proposed applications of the steam-engine about this time, was its employment as a locomotive in driving wheel-carriages. It will be remembered that Watt’s friend Robison had, at a very early period, directed his attention to the subject; and the idea had since been revived by Mr. Edgeworth, who laboured with great zeal to indoctrinate Watt with his views. The latter, though he had but little faith in the project, nevertheless included a plan of a locomotive engine in his patent of 1784; but he took no steps to put it in execution, being too much engrossed with other business at the time. His plan contemplated the employment of steam either in the form of high-pressure or low-pressure, working the pistons by the force of steam only, and discharging it into the atmosphere after it had performed its office, or discharging it into an air-tight condenser made of thin plates or pipes, with their outsides exposed to the wind or to an artificial current of air, thereby economising the water which would otherwise be lost. Watt did not carry his design into effect; and, so far as he was concerned, the question of steam locomotion would have gone no further. But the subject had already attracted the attention of William Murdock, who had for some time been occupied during his leisure hours in constructing an actual working model of a locomotive. When his model was finished, he proceeded to try it in the long avenue leading to the parsonage at Redruth, in the summer of 1784; and in so doing nearly frightened out of his wits the village pastor, who encountered the hissing, fiery little machine, while enjoying his evening walk.[264] [264] ‘Lives of Engineers,’ iii. 77. When Watt heard of this experiment, he wrote to Boulton, advising that Murdock should be gently counselled to give up his scheme, which might have the effect of withdrawing him from the work of the firm, in which he had become increasingly useful. “As to my own part,” wrote Watt, “I shall form no obstacle to the scheme. My only reasons against it were that I feared it would deprive us of a valuable man; that it would, if we were to be concerned in it, divert us from more valuable business, and perhaps prove a sinking fund; and lastly, that I did not like that a scheme which I had revolved in my mind for years and hoped to be able at some favourable time to bring to perfection, if capable of it, should be wrested from me, or that I should be compelled to go into it as a secondary person. But I have now made the latter objection give way. And as to the first, I think it will take place at any rate, so we must make the best of it.”[265] [265] In a letter dated 28th August, 1784, Watt communicated his views to his partner on the subject of locomotive engines at great length. In the course of the letter he says,--